Sealing elements used in downhole fluid recovery operations are a very well known, invaluable and generally available for a variety of applications in downhole fluid recovery operations. Packers, bridge plugs, nipple plugs, are just a few devices that incorporate sealing elements which are needed to separate zones, segregate pressure differentials, etc.
Many sealing elements are composed of elastomeric material as such material lends itself to excellent sealing even in bores that are not perfectly round due to the ability of the elastomer to flow or conform to a surface. The elastomer can thus easily become eccentric upon setting compression being applied.
While sealing elements generally work very well for their intended purpose, they do have limitations. One thing that presents problems for well operators is well conditions having dramatically differing pressures across the sealing element. Such conditions can cause the sealing element to extrude and thereby fail. Prophylactic measures to prevent this occurrence include the provision of metal barriers used to support the sealing element or metal barrier extending from a mandrel or from a tubing or casing segment at which the sealing element is (or is to be) set. The purpose of the barrier is to reduce the open space through which the sealing element could be extruded. One area of concern is the amount of precision possible in nested structures downhole. Such precision is relatively low, due to having to pass through many thousands of feet of wellbore. Therefore, the gap left beyond the barrier is still large enough to allow extrusion of the sealing element therethrough. In addition, because the barriers are only supported on the inside dimension or the outside dimension, and generally not both, they are susceptible to breaking themselves, thereby leaving the packer unprotected from extrusion. There are other areas where extrusion of the sealing element is a concern which will be readily apparent to those skilled in the art of seal design.
The art would welcome a configuration that reliably reduces extrusion of sealing elements.